An Organic Light Emitting Diode (OLED) display device is one of hot topics in a research field of flat-panel displays; as compared with a liquid crystal display, the OLED display device has advantages of low power consumption, low production cost, self-luminous, a wide viewing angle and a fast response speed; and currently, in the field of flat-panel display such as a mobile phone, a Personal Digital Assistant (PDA) and a digital camera, the OLED display device has begun to replace a traditional liquid crystal display.
A structure of the OLED display device mainly comprises: a base substrate and pixels arranged in a matrix on the base substrate, wherein, for each of the pixels, an organic light emitting diode structure is generally formed in a corresponding pixel position on an array substrate with an organic material by using an evaporation filming technology through a fine mask. For color display, it is necessary to colorize the OLED display device. Therein, a color picture using a side-by-side mode has the better effect. The side-by-side mode refers to that within one pixel range, there are three sub-pixels, i.e., red, green and blue (R, G and B) sub-pixels, and each sub-pixel has an independent organic light emitting diode structure. Since organic light emitting materials of the three sub-pixels, i.e., red, green and blue sub-pixels are different, in a fabrication procedure, it is necessary to respectively evaporate three different types of organic light emitting materials for the three primary colors, i.e., red, green and blue sub-pixels in the corresponding positions by a mask, and then a color mixing ratio of a combination of the three colors is adjusted, so as to produce a true color.
A technical focus for fabricating an OLED display device of high Pixel Per Inch (PPI) lies in a fine mask with a good mechanical stability, and a key of the fine mask lies in an arrangement mode of pixels and sub-pixels.